Impacts on fish from piling at offshore wind sites

A study to improve understanding and acceptance of the risk of offshore wind construction on fish spawning grounds

Offshore wind construction activities, such as pile driving, generate noise which can disturb marine life. Due to potential impacts, restrictions and conditions are placed on UK offshore renewables developers during their construction activities when marine mammals and fish are considered to be most vulnerable to disturbance, such as during spawning and migration. It is important to ensure that the established controls are appropriately formulated to deliver a protection benefit without unnecessarily burdening development.

The  ORJIP ‘Impacts on Fish from Piling at Offshore Wind Sites’ project analysed annual fish spawning data in UK waters over the past 10 years to better define fish spawning grounds and to evaluate the potential impacts of new offshore wind sites on Atlantic herring and other fish.

The main spawning sites for the different Atlantic herring stocks in UK waters are well known. However, due to the specific habitat and environmental conditions that herring need to spawn successfully, there are discrete pockets of spawning bed areas that are less easy to identify as they can change from year to year. Currently the exact location of spawning beds can only be identified if they are recorded through grab sampling or by drop down video surveys.  This study aims to address the uncertainty of the accuracy of fish spawning information and the impacts of piling activity on fish species.

The objectives of the study were:

  • Review and consolidate available data and information to define (where possible) UK populations, spawning areas, and periods for key species of concern.
  • Identify any gaps in our understanding of fish populations, spawning areas and periods.
  • Define and gain acceptance with consenting authorities and experts on fish populations, spawning areas and periods.
  • Discuss and understand how the current mitigation approaches are agreed by consenting authorities with the aim to understand what is required to support a change in construction restrictions.


The study launched in Summer 2017 is the first ORJIP study to look in detail about the important subject of fish and wind farm consenting. Below is an example of an Atlantic herring heatmap - an output of the study.

heatmap with footprints

The analysis shifts the focus of studies from abandoned spawning sites and highlights those regions that have shown recent spawning activity. The techniques and methodology of heat mapping demonstrated the final report study provides clearer information of the areas of spawning and their proximity to offshore wind developments. If considered in the consenting process this could lead to a reduction in construction times, potentially lowering cost to consumers, and reducing operational disruption for offshore wind farms.

ORJIP Piling Study Final Report Aug 2018 (PDF)

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